Regin was acquired in a February trade with the New York Islanders. He had two goals and two assists in 17 regular-season games for Chicago.
The Blackhawks were without forwards Brandon Bollig and Andrew Shaw for Sunday night's game. Bollig was suspended for two games for boarding Wild defenseman Keith Ballard in Game 4, and Shaw has been out since Game 1 with a lower-body injury.
Defenseman Michal Rozsival and forward Jeremy Morin also were scratched, putting defenseman Sheldon Brookbank and forward Kris Versteeg back in the lineup.
The Wild played without Ballard (upper-body injury) and forward Matt Moulson (lower-body injury).